KT120 in Audio Research Pre-amp?

I recently exchanged my totally worn out 6550C's for KT120 tubes from Tung Sol in my VT200 MkII. It required a small modification, I'll spare you the details, but it was a succesful operation, quite happy with the sound of the KT120's.
I have some spare KT120's and I was wondering.... is there any danger in replacing the Svetlana 6550C of my Audio Research Reference 3 for a KT120 tube? Since it is a risk-free replacement for most ARC-poweramps, I was wondering if this would be the same risk-free replacement for their pre-amps like a Ref3.